A Case with Thyroid Hormone Resistance Syndrome

ABSTRACT

Thyroid hormone resistance is a rare syndrome of reduced tissue responsiveness to thyroid hormone. We report the case of a 13-month girl with short height and low weight. She was born at 37+6 weeks gestation and weighed 2,470 g. In the neonatal screening test, patients' thyroid stimulation hormone (TSH) level was increased to 13.1 µIU/mL. In follow-up test after getting levothyroxine medication, patients' free T4 level continued to increase and TSH level was normalized. After stop medication, the patient visited Soonchunhyang University Seoul Hospital every 2 to 3 months and done laboratory test, and the result was not changed. Despite good feeding, she consistently shows 5–10 percentile weight and 5–10 percentile height. Her bone age was delayed by 5 months compared to the expected age. In suspicious thyroid hormone resistance, THRβ gene study and brain magnetic resonance imaging (MRI), and T3 suppression test was done. Brain MRI and T3 suppression test shows the exception of pituitary thyroid adenoma. Gene study result was THRβ gene mutation, c.1012C>T (p.Arg338Trp), and heterozygous. This gene mutation was reported at thyroid hormone resistance family. After diagnosis of thyroid hormone resistance, because of the patient is asymptomatic, she does not have medication. We are checking developmental delay, growth delay, and other clinical hypothyroid symptoms.